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← All case files CS-019 / Last reviewed Aug 23, 2026 Jump to sources ↓

Energy & advanced manufacturing / 2017–2020

A departing Phillips 66 scientist copied a flow-battery research library before joining a China-based company

The day before resigning from Phillips 66, Hongjin Tan copied hundreds of research files to a thumb drive. Investigators found deleted copies and a second drive containing battery-development material.

Finding

Tan pleaded guilty to theft and unauthorized possession of trade secrets. The court ordered 24 months in prison and $150,000 restitution; the victim company's $1 billion valuation remains an attributed estimate.

01 / Executive brief

Executive summary

Hongjin Tan worked as an associate scientist on next-generation battery technology at a Phillips 66 research facility. On December 11, 2018, the day before he resigned, he copied hundreds of files to a thumb drive; after returning that drive with five documents deleted, investigators found the same material on another external device. S1S2S3

Tan admitted stealing and possessing protected battery research and was sentenced to 24 months in prison, three years of supervised release, and $150,000 restitution. Phillips 66 told investigators the development effort was worth more than $1 billion, but that figure is a company valuation reported by prosecutors—not a court-calculated loss award. S1S2

Portrait of scientist Hongjin Tan in a laboratory setting
portrait

Hongjin Tan, the former Phillips 66 scientist who pleaded guilty to stealing battery research. The portrait was published from his LinkedIn profile by the South China Morning Post.

Hongjin Tan via LinkedIn / South China Morning Post · Editorial use; all rights remain with the original creator and publisher
Rows of cylindrical battery cells arranged for manufacturing
technology

Battery research combines chemistry, process parameters, test results, and failures into a portable development record. This is contextual technology imagery, not Phillips 66 equipment from the case.

U.S. Department of Energy · Public domain

02 / The vignette

What happened

A laboratory role exposed a whole development program

Tan's work involved energy-storage systems used in stationary applications, including flow-battery technology. His scientist role provided access not merely to one result but to the accumulated experimental record that made the program reproducible and commercially meaningful. S1S2S3

The departure date compressed the risk

Tan copied hundreds of files on December 11, 2018, then submitted his resignation the following day. When the company asked for the thumb drive, he returned it after deleting five documents; investigators later recovered matching copies from another drive. The sequence shows why resignation is a risk event rather than the moment controls should begin. S1S2

A new job created an immediate destination

An official security case study documents Tan's planned employment with Xiamen Tungsten in China. That affiliation supplies commercial context, but Tan pleaded to trade-secret offenses rather than economic espionage, so this dossier does not treat a PRC-state beneficiary as judicially established. S1S3

03 / Anatomy

How access became transfer

This chain reconstructs the sequence supported by the cited record. It does not imply that every legitimate relationship follows the same path.

  1. 01

    Relationship established

    Battery scientist

    Phillips 66 employed Tan in research on high-value stationary energy-storage technology. S1S2S3

  2. 02

    Sensitive access gained

    Development library

    His role exposed him to extensive trade-secret files supporting battery development. S1S2

  3. 03

    Information acquired

    Hundreds of files copied

    Tan copied a large research collection to removable media immediately before resigning. S1S2

  4. 04

    Assets moved

    Two external drives

    Deleted documents from the returned thumb drive remained on a second external device. S1S2

  5. 05

    Technology put to use

    Prospective foreign employment

    Tan had accepted a role with Xiamen Tungsten, creating an apparent destination for his expertise, though no economic-espionage conviction resulted. S3

  6. 06

    Competitive harm

    Prison and restitution

    A guilty plea led to two years in prison and $150,000 in restitution. S1S2

04 / Evidence boundary

What is established—and what is not

Established in the record

  • Tan admitted copying and retaining Phillips 66 battery trade secrets on external media. S1S2
  • The court ordered a 24-month prison term and $150,000 restitution. S2

Uncertain, limited, or unresolved

  • The reviewed record does not establish that the files reached Xiamen Tungsten or a PRC government entity. S1S3

Subject response / procedural context

  • Tan admitted the trade-secret offenses through a guilty plea; the reviewed sources do not include a public response from Xiamen Tungsten. S1S2

05 / Sequence

Timeline

  1. R&D role begins

    Tan began work as an associate scientist with access to battery research. S3

  2. Files copied

    Tan moved hundreds of research files to a thumb drive one day before resigning. S1S2

  3. Guilty plea

    Tan admitted theft and unauthorized possession of trade secrets. S1

  4. Sentence imposed

    The court imposed 24 months, supervised release, and restitution. S2

06 / People and institutions

Who appears in the public record

Hongjin Tan

Former Phillips 66 associate scientist

Outcome: Pleaded guilty; sentenced to 24 months

Xiamen Tungsten

Prospective China-based employer identified in the official case study

Originator / affected institution

Phillips 66

Developer and owner of the battery research

07 / Consequences

Documented and attributed harm

Attributed estimate

Phillips 66 valued the underlying development effort at more than $1 billion; that is the company's attributed estimate, not the restitution amount or a court loss finding. S2

08 / Hindsight analysis

Where leadership could have seen risk

These are our analytic judgments based on the public record, not court findings. They are framed to improve controls without treating nationality as a risk factor.

Resignation followed the copy

The highest-volume acquisition occurred before the employer had the explicit warning supplied by Tan's resignation.

Returning one device was insufficient

Deleted files on a surrendered thumb drive did not account for duplicate copies retained on other external media.

09 / Apply the lesson

Actions leaders can take

  1. companies

    Detect pre-exit staging

    Alert on unusual bulk copying, archive creation, or removable-media use before and immediately after a resignation signal.

  2. companies

    Inventory every copy

    Treat return of one device as the start of forensic accounting, not proof that proprietary material has been recovered.

  3. both

    Separate value from file count

    Prioritize crown-jewel research by replacement time and competitive leverage, even when it occupies only a handful of documents.

10 / Source record

Sources

Links point to the public record reviewed for this file. Government releases can summarize court proceedings but remain government-authored sources; the source note identifies those limits.

  1. S1

    Chinese National Pleads Guilty to Committing Theft of Trade Secrets ↗

    U.S. Department of Justice · Published Nov 12, 2019 · Retrieved Aug 23, 2026

    government release
  2. S2

    Chinese National Sentenced for Stealing Trade Secrets Worth $1 Billion ↗

    U.S. Department of Justice · Published Feb 27, 2020 · Retrieved Aug 23, 2026

    The headline repeats the victim company's valuation; the sentence included $150,000 restitution.

    government release
  3. S3

    Insider Threat Case Study: Hongjin Tan ↗

    Defense Counterintelligence and Security Agency · Published Feb 27, 2020 · Retrieved Aug 23, 2026

    government release